a) Field of the Invention
This invention relates to a stepping motor. More specifically, this invention relates to a structure of the terminals of the stepping motor.
b) Description of the Related Art
Generally, a stepping motor comprises a rotor part having a magnet fixed onto a rotor shaft, a stator part facing the rotor part, a circular coil bobbin, and a coil wound around the body of the coil bobbin.
In order to attain miniaturization of such a stepping motor, in the case of a motor size of less than 10 mm in diameter for example, the bobbin size has been reduced by integrating the coil bobbin into the inner stator core constituting the stator part by means of insert molding.
Furthermore, when the motor size is less than 5 mm in diameter in which a coil bobbin is molded with the inner stator core as an integrated body, the coil bobbin occupies a large proportion of the motor. As a result, the required winding space cannot be secured and the needed motor torque cannot be obtained.
To overcome this problem, an insulating film is formed on the surface of the stator core, and the coil bobbin is omitted to eliminate the proportion occupied by the coil bobbin. A stepping motor having an elongated space for coil winding has been thus developed (see Unexamined Japanese Patent Application Publication No. 2004-112985, for example). In a stepping motor of this type, terminals are provided at the side planes of the coil windings. As illustrated in FIG. 11, terminal 100 is made up of a pin which is formed integrally with bobbin 101 and terminal block 102 by insert molding. And terminal part 103 of the coil windings is wound around terminal 100.